Vanalli, C.; Falvo, C.; Crowley, D.; Schwarz, B.; Plowright, R.; Hudson, P. J.; Rynda-Apple, A.; Cattadori, I. M.

Changes in the quality and quantity of food resources can affect individuals\' health, the way they control infections and consequently the likelihood of onward transmission of pathogens. Dietary shifts have been proposed as one of the factors driving spillovers of zoonotic viruses from bats through a bridging host to humans. While there is a general understanding of the relationship between nutrition and infection in model systems, how diet affects pathogen shedding and the risk of spillover from bats is lacking. We used a data-driven mathematical modeling approach to disentangle the relation between diet, immunity, and viral shedding of Jamaican fruit bats infected with H18N11 and fed different dietary regimes. Model selection indicates that the synergistic interaction between the metabolite citrulline and the cytokine TNF controls viral shedding in a diet-dependent manner. Bats on a sub-optimal fat diet are more successful in terminating shedding than bats on an optimal or sub-optimal sugar diet. However, when bat foraging behavior is considered, bats on the optimal diet show a lower spillover hazard, probably because of a feeding behavior less conducive to transmission. This study provides novel insights into the diet-driven mechanisms of viral shedding and how they can potentially contribute to spillover events.